江西西部一次局地对流性暴雨过程诊断分析

周永生

摘要 利用Micaps常规资料、多普勒雷达资料、地面加密自动站点资料，从环流形势、物理量场、回波特征方面，诊断分析了2014年5月24日08∶00—25日08∶00江西西部局地对流性暴雨天气过程。结果表明，这次对流性暴雨是在亚欧中高纬度环流经向度较大及副热带高压边缘扰动气流的背景下，中低层低槽和切变线共同影响下发生的；西南低空急流的建立、西南暖湿气流的增强，为这次对流性暴雨的产生提供了丰富的水汽、动力和热力条件。低层辐合、高层辐散和强烈的上升运动是产生这次对流性暴雨的重要动力条件；中低层有大的水汽积聚和水汽输送是产生这次对流性暴雨的重要水汽条件；大气层结不稳定、存在产生较强对流的有利条件、高能量区与中低层湿区和急流配合是产生这次对流性暴雨的重要热力条件。这次暴雨过程在雷达回波上以对流性回波为特征，出现2个主要降水时段（24日20∶00—25日01∶14、25日01∶24—09∶00），其中第2个降水时段维持降水时间长、降水强度大，是这次对流性暴雨的主要降水时段。

关键词 局地对流性暴雨；环流特征；物理量；雷达回波

中图分类号 S165 文献标识码 A 文章编号 0517-6611（2017）07-0163-05

Diagnostic Analysis of a Local Convective Rainstorm in Western Jiangxi

ZHOU Yong-sheng

（Jian Meteorological Observatory， Jian， Jiangxi 343000）

Abstract Using Micaps data， doppler radar， ground encrypted automatic station data， a local convective rainstorm in Western Jiangxi during 08∶00 May 24-08∶00 May 25 in 2014 was analyzed from aspects of circulation situation， physical quantity， echo characteristics. The results showed that the rainstorm was under the influence of the middle and low trough and shear line； the establishment of southwest low level jet， enhancement of the southwest warm and humid air， provided abundant water vapor， dynamic and thermal conditions for the generation of convective rainstorm. Low level convergence and upper level divergence and strong ascending motion were important driving conditions of the convective rainstorm； in the middle and lower layers， the water vapor accumulation and water vapor transport were the important water vapor conditions； unstable atmospheric stratification， favorable conditions for the existence of strong convection， and the high energy zone and the middle and low wet zone and jet flow were the important thermodynamic conditions for the convective rainstorm. The rainstorm process was reflected by convective radar echo， which is characterized by two main precipitation periods （20∶00 May 24-01∶24 May 25，01∶24-09∶00 May 25）. The second precipitation period maintained long time and high intensity， which is the main precipitation period of the rainstorm.

Key words Local convective rainstorm；Circulation characteristics；Physical quantity；Radar echo

暴雨的產生是各种天气尺度系统共同作用的结果，许多学者对此进行过深入研究[1-5]。朱乾根等[1]描述了暴雨发生的大尺度环流背景及产生暴雨的天气系统基本原理，给出了暴雨及强对流发生的基本条件；林确略等[6]基于对锋面、锋前暖区及高压后部暴雨进行了大尺度环流背景和中尺度特征对比分析，探讨了在天气形势、中尺度系统发生对暴雨发展机制等方面的差异及原因。……